In the U.S.A. in 1997 there were approximately 800,000 inadvertent needle sticks to health care workers that resulted in approximately 2,000 cases of hepatitis C and 35 cases of HIV infection. Inadvertent needle sticks could be avoided if blunt tip injection needles were used to deliver medication to the patients. However, such injections would be very painful to the patients unless they were placed through a percutaneously placed catheter device such as an injection set that uses a subcutaneous cannula as described in U.S. patent application Ser. No. 09/110,360 entitled, "DEVICE FOR SUBCUTANEOUS INJECTION". Although that patent application describes an appropriate injection set, it only describes the use of blunt needles attached to a hypodermic syringe and does not describe the use of a pen-type injector having a blunt needle attached for administering medication to a patient.
In U.S. Pat. Nos. 5,599,323 and 5,728,074 two different types of pen-type injectors are described in detail. These pen-type injectors are now in use throughout the world as an improved means for delivering a preset dosage of medication. However, all such pen-type injectors use removable needles that have sharp points that can cause inadvertent needle sticks to the health care worker that uses them in a hospital or nursing home situation.